The present invention relates generally to self-adjuvanting vaccines for use in raising antibodies to peptides without the use of oil or alum adjuvants. The present invention further relates to the use of this vaccine and to methods of therapy. The present invention has particular application in chemical castration.
The use of leutinising hormone releasing hormone (LHRH) in chemical sterilisation of both male and female immunized with preparations including LHRH and this immunisation leads to dysfunction of the gonads and consequent induced sterility. In male animals reduction in testicular size relative to untreated controls may be clearly seen. Unfortunately, the mere immunisation with LHRH is not a totally effective method of chemical castration. Typically, whilst in the majority of one group of animals the immunisation with LHRH will have the desired effect, the immunisation will have little effect on a number of animals in that sample. As will be readily appreciated this is a significant drawback because, for example, if one unaffected male remains in the immunised herd this male may fertilise a number of females within the herd. For this reason chemical sterilisation utilising LHRH has to date achieved only limited application, with physical and other methods of sterilisation still predominating.
In the present applicant's copending Austrailian patent application No 17049/88 there is disclosed an effective method of peptide production by protein engineering. This method involves the culturing of genetically engineered bacteria which produce, as extracellular structures, Type 4 fimbriae, the peptide being produced in association with these fimbriae. This method comprises culturing bacteria containing the gene encoding the fimbrial subunit of Type 4 fimbriae to which has been added at the C-terminal end the nucleic acid sequence encoding the desired peptide. In further work on this system the present inventors have found that not only does this method provide a simple and efficient means of producing a peptide but that the fimbrial protein acts as a powerful immunoadjuvant.
The present inventors have also produced a peptide having a sequence derived from LHRH in association with Type 4 fimbriae. It has been found that this peptide conjugated to bacterial Type 4 fimbriae provides a very effective chemical sterilisation agent.
In the present applicant's copending International Patent Application No PCT/AU90/00599 (the disclosure of which is incorporated herein by reference) there is disclosure of means of linking fatty acids and the like to peptides.
The present inventors have also found that co-administration of a peptide/fatty acid conjugate with a peptide/carrier protein (such as fimbrial protein) conjugate yields a heightened antibody response to the peptide.
In addition the present inventors have found that the antibody response in an animal can be enhanced by the use of the fimbrial protein of a Type 4 fimbriate bacteria.